High-Resolution Mass Spectrometry Identification of Micropollutants Transformation Products Produced During Water Disinfection With Chlorine and Related Chemicals

Reaction of diazepam and related benzodiazepines with chlorine. Kinetics, transformation products and in-silico toxicological assessment

“…Also, potassium bromide was added at 0.05-0.1 µg mL -1 in some experiments. These pH values and bromide concentrations, which is known to react to HBrO with chlorine, were selected as to represent typical surface waters (Gonzalez-Marino et al, 2016). After free chlorine addition at concentrations in the 0.5-10 µg mL -1 range, also representing typical dosages during drinking water production (Gonzalez-Marino et al, 2016), the amber vials were manually shaken for 2-3 s. Then, 6-10 aliquots of 1 mL were collected at increasing reaction times, from time 0 s (before chlorine addition) to 120 min-96 h (depending of the reaction rate of the drug).…”

“…chlorine, ozone, chloramination, chlorine dioxide, H 2 O 2 , ferrate or UV radiation (Postigo and Richardson, 2014;Sharma, 2008). However, such disinfectants agents can generate a range of transformation products (TPs) which are sometimes more toxic than the precursor compound (Gonzalez-Marino et al, 2016;Postigo and Richardson, 2014). In the case of benzodiazepines, photodegradation (Calisto et al, 2011;Jakimska et al, 2014;Kosjek et al, 2011;West and Rowland, 2012) and hydrolysis (Cabrera et al, 2005;Han et al, 1977) have been previously reported as well as the advanced oxidative treatments (Bautitz and Nogueira, 2010;Bautitz et al, 2012).…”

“…For those benzodiazepines reacting in a significant degree, parameters affecting to the kinetics, such as pH, chlorine and bromide content were studied in detail. Further, TPs were tentatively identified by using liquid chromatography (LC) and high resolution mass spectrometry (HRMS) (Bautitz et al, 2012;Calisto et al, 2011;Gonzalez-Marino et al, 2016;Jakimska et al, 2014;Kosjek et al, 2011), with a quadrupole-time of flight (QTOF) system. Finally, a preliminary evaluation of the ecotoxicity of the TPs was performed using quantitative structure-activity relationship (QSAR) tools and the magnitude of the reaction was assessed in real environmental water matrices.…”

Integrated Framework for Identifying Toxic Transformation Products in Complex Environmental Mixtures

“…Transformation products (TPs) encompass a large proportion of unregulated chemicals present in the environment and may be equally, if not more, persistent and toxic than their precursor chemicals. ,,− While the characterization of TPs by NTA has been focused primarily on wastewater treatment plants, − prior studies have also shown the formation of TPs in chemically treated water − and in natural water. − Other toxic TPs include metabolites of pharmaceuticals and pesticides in wastewater and groundwater, ,,− such as persistent methylated derivatives from the antimicrobial triclosan . Concerns over the formation of toxic TPs during remedial applications, ,,, and from environmental photo-oxidation reactions, ,− have also been raised.…”